1. Field of the Invention
This invention relates to a heater assembly for melting and dispensing hot melt adhesives and similar materials.
2. Description of the Related Art
Hot melt adhesives are widely used for a variety of purposes ranging from industrial to household applications. Often, hot melt adhesives are dispensed by a hand-held applicator which may be conveniently manipulated to deliver molten adhesive directly to an application site. Applicators of this type normally have a heated melting chamber of a truncated cone shape that is adapted to receive and melt elongated blocks of solid thermoplastic adhesive and dispense the molten adhesive through an outlet.
Melting chambers of hot melt applicators are formed within a heating block that is made of metallic materials exhibiting a high thermal conductivity. In some instances, these heating blocks have a cylindrical compartment that is below the melting chamber and which receives a slide-in electrical heating element having an elongated external casing of matching cylindrical shape. Typically, the single heating element of such heater assemblies extends in a direction that is either parallel or somewhat inclined relative to the central longitudinal axis of the truncated conical melting chamber.
Heater assemblies of hot melt applicators are occasionally provided with two or more heating elements in an attempt to increase the available thermal energy and to improve heat distribution to the melting chamber. In some instances, elongated heating elements are located on opposite sides of the melting chamber in an orientation such that the longitudinal axis of each heater and the central axis of the melting chamber all extend in parallel directions in a common plane. However, such construction requires a somewhat bulky heating block which increases the weight of the applicator and hinders observation of the work site.